Liquid mixing device



Sept. 8, 1964 c. F. MARTIN 7,

' LIQUID MIXING DEVICE Filed May 31, 1960 2 Sheets-Sheet 1 (flaw/es f7 MO INVENTOR.

BY w, fip

ATTORNEY Sept. 8, 1964 c. F. MARTIN LIQUID MIXING DEVICE 2 Sheets-Sheet 2 Cfiar/ea f: Marf/fl INVENTOR.

m Tmm Filed May 51. 1960 ATTORNEY United States Patent 3,147,957 LIQUID MIXING DEVICE Charles F. Martin, W. J. Cooper, 813 Chronicle Bldg,

Houston, Tex., assignor of twenty-five percent to Warner J. Cooper, Houston, Tex.

Filed May 31, 196i), tier. No. 32,706 Claims. (Ci. 259%) This invention relates to a mixing device, as to a device for mixing two or more different liquids in order to obtain a completely Uniform admixture of the liquids involved.

It is a primary object of the invention to provide a liquid mixing device capable of drawing two or more liquids thereinto in a manner to direct the liquids together within the device to be retained therein a minimum length of time while a maximum shearing effect is imparted thereto whereby maximum mixing is obtained.

It is also an object of this invention to provide a mixing device of this class in which impellers mounted on concentric shafts rotating in opposite directions draw fluid into oppositely mounted hub ends and discharge the fluid into adjacent, slightly spaced apart, face to face mounted discharge ends wherein the liquid to be mixed are retained a minimum length of time while a maximum shearing effect is imparted thereto by virtue of the liquids being rolled in the impeller portions with a maximum shearing effect and number of shears.

It is a further object of this invention to provide a mixing device of this class which i easily assembled, positive in operation, revolutionary in effect, inexpensively produced, and which has a minimum number of working parts.

Other and further objects will be apparent when the specification herein is considered in connection with the drawings in which:

FIG. 1 is an elevational view showing the invention mounted in a liquid filled container with the drive means indicated diagrammatically;

FIG. 2 is a sectional elevation of one embodiment of the invention showing details of impeller construction and also details of mounting the impellers on their respective shafts;

FIG. 3 is a plan view, part in section, taken along line 33 of FIG. 2 disclosing upper inlet flow passage arrangement;

FIG. 4 is a bottom view part in section, showing the upper impeller, and taken along line 44 of FIG. 2;

FIG. 5 is a bottom view, part in section, showing the lower impeller and taken along line 55 of FIG. 2;

FIG. 6 is a fragmentary development view, partially diagrammatic, showing impeller discharge end construction and emphasizing the mixing effect obtained therein; and

FIG. 7 is a modification of the invention showing a variation in the construction of the vanes separating flow passages.

Referring in detail to the drawings in which like reference numerals are assigned to like elements in the various views, a mixing device 10 is shown in FIG. 1. This mixing device comprises an outer shaft 11 having an upper impeller 12 mounted thereon, and an inner shaft 13 having a lower impeller 14 mounted thereon. Such mixing device 10 is shown inserted into a container 15 having two or more different or dissimilar liquids therein filling the container up to the level 16. The mixing device may be supported in numerous ways as by an ogive 17 assembled with the lower impeller 14 to rest on the bottom of the container 15, or optionally the mixing device may be suspended and supported by a collar 18 shown diagrammatically on top of the container cover 19. Drive means 20 and 21 are indicated for driving 3,147,957 Patented Sept. 8, 1964 'ice the respective inner and outer shafts 13 and 11 in opposite directions.

As shown in greater detail in FIG. 2, the inner shaft 13 has as its lower portion a slightly larger diameter part 22 and a threaded lower terminal part 23 of reduced diameter. The lower impeller 14 includes a housing 24 including a lower cylindrical hub or hub portion 25 and a larger diameter outwardly flared, discharge flange or portion 31. As best seen in FIG. 2, the hub portion 25 and discharge flange 31 are connected or integrally formed. Also the impeller 14 includes an inner portion or member 26 spaced above the hub portion 25 and inwardly of the housing 24.

Blades, partitions or vanes 30, generally extending vertically, connect and space apart the inner peripheral, convexly arcuate surface 57 of the discharge flange 31 and the outer peripheral eoncavely arcuate surface 58 of the inner member 26. Referring to FIG. 2, such surface 58 is shown as extending upwardly, from the lower, smaller diameter end 56 of the inner member 26, to an outer diameter or periphery 51 at the top, where the member provides a flat annular surface or face 52 with outer diameter that of the periphery 51, such diameter being substantially greater than the diameter of the inner periphery of the hub through which fluid enters, and substantially less than the outer diameter or peripheral dimension 55 of the discharge flange 31. The lower impeller inner portion 26 including generally mean to connect it to the inner shaft 13 and to this end the smaller end 56 of the inner member 26 is bored to receive the larger diameter shaft part 22 therethrough. A plate 27 is bored to be fitted over the threaded shaft part 23 and such plate 27 has a bolt circle or ring of bores 28 therethrough of some diameter greater than the diameter of the shaft portion 22 with cap screws 29 extending through the bores 28 and tapped into the inner portion 26 of the impeller whereby the cap screw heads bear against the lower surface of the plate 27 to firmly assemble the plate 27 with its outer upper surface to bear against the lower face of the impeller inner portion 26 and with its inner upper surface to be abutted by the lower shoulder surface of the enlarged diameter shaft part 22.

The ogive 17 is tapped to threadedly receive the shaft end part 23 and counterbored to provide a recess to receive therein the plate 27 and cap screw heads 29 and to receive the shaft end part 23 therethrough so that the annular upper face of the ogive outwardly of the plate 27 bears tightly against the impeller inner portion 26 whereby the plate 27, cap screws 29, and shaft end 23 are completely enclosed and protected, and whereby the assembly of shaft, ogive, and impeller is completed.

The vanes are in effect partition walls 30 which divide the outer portion of the space between housing 24 and inner member 26 into a plurality of flow passages or compartments. Such vanes 30 begin inwardly with inner or inlet opening from the hub 25 into the vanes extending between the upper, inner corner of the hub 25 and the lowermost outer corner or lowermost surface periphery of the impeller inner portion or member 26, and from inlet the vanes 30 extend generally in vertical planes, with opposed edges extending longitudinally and radially of the impeller axis along the respective inner arcuately convex surface 58 of the discharge flange 31 and the outer arcuately concave surface 57 of the flange 32 of the impeller inner portion or member 26. The vanes 30 further extend outwardly of the outer diameter or pe riphery 51 of the flange 32 and to a distance equal to the outer diameter or periphery 55 of the flange 31, and with upper edges 54 spaced above the inner surface of the flange 31.

Thus, as best seen in FIG. 2, upper edges 54 of the vanes 30 lie in substantially the same horizontal plane with the upper surface or face 52 of the flange 32, whereby the distances of the vane upper edges 54 above the inner surface of the discharge flange 31 define di mension at the outlet opening or periphery 55 of the impeller discharge outlet 45.

An annular spacer 33 fits about the inner shaft 13 and bears upon the upper shoulder of the enlarged diameter shaft portion 22. The outer shaft 11, which is tubular to fit about the inner shaft 13 as a sleeve, has a lower portion 34 counterbored to provide a recess 35. An antifriction member, as a roller bearing assembly 36, indicated diagrammatically in FIG. 2, is press-fitted into the upper end of the recess 35 and such recess has therein successively therebelow a washer 37, a seal ring 38 of resilient material, and a washer 39. When the outer shaft 11 surrounds the inner shaft 13 as a sleeve, the Washer 39 and outwardly thereof the annular end face of the outer shaft portion 34 bears upon the spacer 33.

The upper impeller 12 has a housing 24 and vanes 35) constructed identically as the housing 24 and vanes 30 of the lower impeller 14. The upper impeller 12 also has an inner portion or member 4-0 which is flared outwardly and downwardly from its upper end to provide a flange 41 of substantially the same diameter at outer periphery 51 as the lower impeller flange 32, and thus the upper impeller flange 41 provides a face 53 of the same outer diameter as the lower impeller flange 32, and to rotate immediately thereabove, only as spaced therefrom by thickness of the spacer 33. Such upper impeller inner member or portion 40 is internally left hand threaded at 42 as its means for connection to the externally left hand threaded terminal part of the outer shaft lower portion 34 whereby to connect these two members and to insure against backing off therebetween in operation, the inner shaft lower end 23 and the ogive 17 being oppositely, or right hand threaded.

Above the threads 42 the outer shaft lower Portion 34 extends outwardly beyond the top outer diameter of the upper impeller inner portion or member 40 to form a flange 43 against the under face of which the upper end face of the upper impeller inner portion 40 firmly abuts when it is threaded full upon the outer shaft lower portion 34. Such flange 43 tapers upwardly at 44 in the form of a frusto-cone to join the upper tubular or sleeve portion of the outer shaft 11.

The upper impeller 12 has a housing 24 of the same construction as the housing 24 of the lower impeller 14, the upper impeller 12 being reversely mounted as regards the lower impeller 14 whereas its housing hub 25 is uppermost and the flange 31 thereof is lowermost. The upper impeller housing 24 and inner portion are interconnected by blades, partitions, or vanes 30 similarly constructed and of the same number and spacing as the vanes 30 of the lower impeller 14.

The spacing between the respective housings 24 and the impeller inner portions 26, 40 is such that preferably there is no choking of any opening, passageway, or flow passage between adjacent vanes, but instead there is best a gradual increase of cross-sectional area between any two adjacent vanes from the liquid entry into the hubs to the fluid outlet at the peripheries 55 from the discharge outlets 45, from the impellers. However, in the case of handling light liquids and fluids of low surface tension and great fluidity, it can be profitable to choke the flow passage area between vanes at some point between inlet and discharge for the purpose of insuring more efficient mixing by the opposed impellers.

As shown in FIG. 6, the mixing fluids are rolled in the process of each shearing effect which takes place during the passage of each flow passage 46 over the flow passage 46' opposed thereto. This rolling effect is obvious since the lower impeller in moving clockwise imparts a clockwise roll to the liquid therein while the upper impeller moving counterclockwise also imparts a clockwise roll to the fluid therein. Thus the liquid is not only profusely rolled but at the same time it undergoes a great number of shearing effects equal to the square of the number of flow passages in an impeller for each rotation of the impellers, assuming the impellers to be rotating at substantially the same speed. It can thus be seen that a machine is attained by this invention which can produce the greatest mixing force by drawing fluid downwardly and discharging it outwardly in an upper impeller while drawing fluid upwardly and discharging it outwardly in a lower impeller, the impellers being spaced apart a minimum practical distance in operation.

The shape of the blades or vanes admits of substantial variation. For instance, the type of vane shown in FIG. 7 discloses the vanes 47 of an upper impeller 12 to be serrated outwardly of the impeller inner portion flange 41 as are the blades or vanes 48 of the lower impeller 14 complementary serrated, whereby fluid in passage outwardly of the respective inner portion flanges 41', 32 is stirred transversely or at right angles to its outward direction of movement as the teeth or serrations 49, 50 passed therethrough interrupting in degree the rolling effect and thereby attaining additional mixing of the liquid.

The invention is thus not limited to the exact constructions, modifications, variations or embodiments disclosed in the drawings and hereinabove described but other forms thereof are included as well as such may fall within the broad spirit of the invention and within the broad scope of interpretation claimed for, and merited by the appended claims.

What is claimed is:

l. A mixing device for mixing two different materials, said device including two concentric shafts each having impeller end portions with the inner shaft end portion extending axially beyond the adjacent outer shaft end portion, an impeller mounted on each end portion and including an inner member having a smaller diameter end and being connected to the respective shaft end portion and larger diameter proximate end faces spaced from said smaller diameter end portions, whereby said end faces are mounted in face to face relation separated only by clearance for rotation, such inner member providing an outer peripheral surface extending from its smaller diameter end to its larger diameter end face, each impeller including a plurality of vanes perpendicular to its inner member end face and disposed in equally angularly spaced apart radial planes around said inner member, each vane having an inner edge for connection to the inner member of its impeller and having a portion extending radially outwardly and lying in the plane of the end face thereof and having a substantially larger diameter than said end face diameter, each impeller also including a housing comprising a cylindrical hub having an inlet end, and also having a downstream portion, said housing also including a discharge flange having a smaller diameter end extending from said hub to the larger diameter end of said vanes and also providing an inner peripheral surface connected to the outer edges of said vanes whereby said housing is spaced concentrically from the respective inner member thus to provide a material inlet, and to space its discharge flange larger diameter ends longitudinally apart to provide discharge space therebetween outwardly of the respective inner member end face, said vanes thereby dividing said impeller into passages equal in number to said vanes, said device including drive means connected to rapidly rotate said shafts at substantially the same rate in opposite directions whereby said material to be mixed is drawn into said hubs and delivered past said end faces, said material thereby to be sheared, over an area equal to that of a segment defined between two adjacent vanes and between discharge flange larger diameter and inner member end face diameter, a number of times per minute calculated to be equal to the product of shaft r.p.m. by the square of the number of passages in an impeller, thus to mix said materials to a high degree of homogeneity.

2. A mixing device for mixing two diiferent materials, said device including two concentric shafts having adjacent impeller ends with the impeller end of the inner shaft extending axially beyond the impeller end of the outer shaft, an impeller mounted on the impeller end of each shaft and each impeller comprising a housing having an end of smaller diameter defining a cylindrical hub, said hub having an inner peripheral surface, said housing also including an end of larger diameter and a discharge flange having an inner peripheral surface extending from said hub inner peripheral surface outwardly to said larger diameter end and having a portion lying in a plane at right angles to the axis of the respective impeller shaft, each impeller also including an inner member having a smaller diameter end and being connected to the respective shaft, and a larger diameter end face spaced from its smaller diameter end and of smaller diameter than said discharge flange, said larger diameter end face being disposed in face to face relationship with the other impeller end face with only clearance for rotation therebetween, said inner member providing an outer peripheral surface to extend from its said smaller diameter end to its said larger diameter end face, each impeller including substantially the same plurality of partition Walls which extend perpendicular to said end face and which have spaced apart outer and inner edges, said partition walls being equally angularly spaced apart in radial planes with outer edges connected to said discharge flange inner peripheral surface and with inner edges connected to said inner member outer peripheral surface, said partition walls extending outwardly beyond said inner member end face to said larger diameter housing end and dividing each impeller into passages equal to the number of partition walls therein, said device including drive means connected to rapidly rotate said impellers at substantially the same rate and in opposite directions whereby the materials to be mixed enter said hubs and upon passing said end faces are sheared, over an area equal to that of a segment defined between two adjacent partition walls and between inner member end face diameter and discharge flange larger end diameter, a number of times per minute calculated to be equal to the product of shaft r.p.m. multiplied by the square of the number of passages in an impeller whereby to mix said materials to a high degree of homogeneity.

3. A mixing device as claimed in claim 2 in which said impeller end of said outer shaft is recessed and in which said device includes a bearing assembly in said recess between said outer and inner shafts and also includes a seal in said recess axially outwardly of said bearing assembly disposed about said inner shaft to protect said bearing assembly from said materials to be mixed.

4. A mixing device as claimed in claim 2 in which said flange inner peripheral surface is convex, and in which said inner member outer peripheral surface is concave.

5. A mixing device as claimed in claim 2 in which said outer shaft impeller end is externally threaded and in which the smaller diameter end of the inner member on said outer shaft has a threaded bore therethrough the aforesaid connection of the smaller diameter end of said outer shaft to the respective inner member is effected by threaded engagement.

References Cited in the file of this patent UNITED STATES PATENTS 1,028,869 Fay June 11, 1912 1,406,355 Donaver Feb. 14, 1922 1,949,696 Schoneborn Mar. 6, 1934 2,121,918 Leighty June 28, 1938 2,778,614 Koch Jan. 22, 1957 FOREIGN PATENTS 648,783 Germany Aug. 9, 1937 

1. A MIXING DEVICE FOR MIXING TWO DIFFERENT MATERIALS, SAID DEVICE INCLUDING TWO CONCENTRIC SHAFTS EACH HAVING IMPELLER END PORTIONS WITH THE INNER SHAFT END PORTION EXTENDING AXIALLY BEYOND THE ADJACENT OUTER SHAFT END PORTION, AN IMPELLER MOUNTED ON EACH END PORTION AND INCLUDING AN INNER MEMBER HAVING A SMALLER DIAMETER END AND BEING CONNECTED TO THE RESPECTIVE SHAFT END PORTION AND LARGER DIAMETER PROXIMATE END FACES SPACED FROM SAID SMALLER DIAMETER END PORTIONS, WHEREBY SAID END FACES ARE MOUNTED IN FACE TO FACE RELATION SEPARATED ONLY BY CLEARANCE FOR ROTATION, SUCH INNER MEMBER PROVIDING AN OUTER PERIPHERAL SURFACE EXTENDING FROM ITS SMALLER DIAMETER END TO ITS LARGER DIAMETER END FACE, EACH IMPELLER INCLUDING A PLURALITY OF VANES PERPENDICULAR TO ITS INNER MEMBER END FACE AND DISPOSED IN EQUALLY ANGULARLY SPACED APART RADIAL PLANES AROUND SAID INNER MEMBER, EACH VANE HAVING AN INNER EDGE FOR CONNECTION TO THE INNER MEMBER OF ITS IMPELLER AND HAVING A PORTION EXTENDING RADIALLY OUTWARDLY AND LYING IN THE PLANE OF THE END FACE THEREOF AND HAVING A SUBSTANTIALLY LARGER DIAMETER THAN SAID END FACE DIAMETER, EACH IMPELLER ALSO INCLUDING A HOUSING COMPRISING A CYLINDRICAL HUB HAVING AN INLET END, AND ALSO HAVING A DOWNSTREAM PORTION, SAID 